The present invention relates to an expander device, particularly for use in expanding springs, piston rings, circlips and similar objects.
There are already known various devices of the type here under consideration which, generally speaking, are used for either expanding or compressing springs, piston rings, circlips or similar objects prior to the mounting of such objects at the locations of intended use, or prior to removal of such objects from such locations. In one of such devices, which is intended for use in spreading apart the ends of a split piston ring, the structural elements which constitute the device include a pair of levers and a pair of jaws, the latter being provided with abutment portions which contact and engage the ends of the respective piston ring, the jaws being connected to the levers by means of a pair of connecting links. In this conventional device, each of the levers forms a parallelogram linkage with the associated connecting links and with the associated jaw. A spindle is provided which has threads of opposite pitches and a pair of nuts is provided each of which is pivotally mounted on one of the levers and threadingly engages the respective threaded portion of the spindle. This device is disadvantageous in that the user of such a device needs both hands for operating such a device.
Another expander device also known to the prior art is similar to the previously described device in that it also includes a pair of levers, a pair of jaws, and a pair of connecting links. However, in this device the levers are pivotally connected at different points to a connecting element and are in positive engagement with one another. This device includes a pair of pressing arms which have front ends and are pivoted at such front ends to the levers, such arms acting upon the jaws so as to spread the same apart. While it is true that in this embodiment the user of the device can spread the jaws apart by using only one hand, such operation requires a rather substantial amount of force. It will be appreciated that such a force will have to be maintained for an extended period of time while the piston ring is either removed from its position on the piston, on the one hand, or located on the piston in its proper position, on the other hand. A disadvantage which is encountered in both of these embodiments is that such devices are so constructed as to be able to cooperate with rings of particular dimensions, and cannot be modified without complete reconstruction for use with rings of different dimensions.